In 2013, the Timbers conceded a Western Conference-low of 33 goals (second in MLS).

And during preseason and the first two games of the regular season, the Timbers have not given up a goal from the run of play. In fact, Portland hasn't given up a goal from the run of play in the last 461 minutes of regular season play, dating back to last season.

“I think it’s partly because we defend as a team," Timbers coach Caleb Porter said. "I think the natural thing is to always credit the backs and the goalkeeper for that, and they’re a big part for sure, but I think it’s also the defending as a team."

The Timbers philosophy also allows them to avoid giving up goals from the run of play. Portland usually controls possession, enabling them to spend less time defending.

Instead, when teams score on the Timbers, it's often off of set pieces.

The Timbers conceded 11 goals from set pieces last season, tied for the fourth-most in MLS. And they have continued to work on set piece defending this year.

But, even though the Chicago Fire took eight corner kicks and were fouled by the Timbers 16 times Sunday night, Portland prevented Chicago from scoring a goal off of a corner kick or free kick. The Fire's lone goal came on a penalty kick.

"They had a lot of balls in the box between corners and free kicks, and we didn’t give up a goal on those," Porter said. "It is a positive to see an improvement in that regard."